Abstract:

Sensory, chemical and microbiological characteristics of cultured Oreochromis niloticus stored aerobically at low from 0 to 10 degree and ambient temperatures at 25 degree were carried out, and the shelf lives and bacterial flora at the end of shelf life were also studied, meanwhile the predictive model of shelf life using square-root relative spoilage rate equation was developed. The results showed that the freshness of cultured Oreochromis niloticus at the initial time was excellent, its mean values of total viable count, Pseudomonas spp count, H2S-producing bacteria count and total volatile basic nitrogen were 4.41±1.13、3.39±1.09、2.01±0.88 lg(cfu/g)和8.53±0.73mg/100g, respectively. The freshness index including total viable count, Pseudomonas spp count, H2S-producing bacteria count and total volatile basic nitrogen of cultured Oreochromis niloticus stored aerobically at low temperature reached 7.79±0.35、7.24±0.45、6.35±0.23 lg(cfu/g)和19.90±2.10mg/100g，the shelf life of fish stored at low temperature was from 5.5 days to 20.1 days, their dominated bacteria was Pseudomonas spp. The shelf life was 1.1 days at ambient temperature , its dominated bacteria was Aeromonas spp. The parameter(minimum temperature) of quality kinetics model of cultured Oreochromis niloticus stored from 0℃ to 25℃ was -8.9℃.The shelf life models of relative rate of spoilage were validated under isothermal (3and 8℃) and non-isothermal conditions,indicating the predictive model of shelf life can efficiently evaluate the quality of cultured Oreochromis niloticus stored from 0℃ to 25℃.